Yarn tensioning device



Aug. 6, 1963 Filed March 20, 1961 D. J. MINDHEIM ETAL YARN TENSIONING DEVICE Sheets-Sheet 1 1963 11.1. MlNDHElM ETAL 3,100,091

YARN TENSIONING DEVICE Filed March. 26, 1961 2 Sheets-Sheet 2 United States Patent 3,100,091 YARN TENSIONING DEVICE Daniel J. Mindheim, Glen Cove, and Howard C. Lindemann, Westhury, N.Y., assignors to Lindley & Cornpany, Incorporated, Mine'ola, N.Y. a corporation of New York Filed Mar. 20, 1961, Ser. No. 123,914 14 Claims. (Cl. 242-150) The present invention relates to yarn tensioning equipment and more particularly to magnetically operated yarn tension-ing equipment.

In warping and other textile processes tensioning of yarn is accomplished by tensioning devices in which the yarn is passed between friction disks which are urged towards each other by a force that can be varied as desired. Heretofore, weights and springs have been used to provide this force. In our application, Serial No. 706,823, filed January 2, 1958, now Patent No. 2,907,535, the use of electromagnetic force is disclosed. This force permits the easy electrical control of tensioning units and insures a much greater convenience and uniformity in the setting of tensioning forces than has been heretofore practical. The electromagnetically operated tensioning devices have been found to operate best with pulsating DC. power. Sources of this type of power are not readily available in many places thus limiting the use of the invention.

It is an object of this invention to provide a compact self-contained tensioning unit, which can be plugged into any common 110 volt or 220 volt AC. outlet.

Another object of the invention is to provide an improved means for applying electromagnetic force to operate a yarn tensioning device.

Other objects and features will become apparent from the following description, claims and drawings in which:

-'FIG. 1 is a view partially in cross-section and partially in side elevation illustrating a yarn tensioning device in accordance with the invention.

FIG. 2 is a schematic diagram of the electrical circuit of the invention as illustrated in FIG. 1.

FIG. 3 is a plan view of the invention showing the yarn tensioning device and the path of the yarn in the device.

FIG. 4 is a cross-sectional view of a yarn tensioning device illustrating a modification.

FIG. 5 is similar to FIG. 4 illustrating another IIlOdl-. fication of yarn tensioning device. 4

FIG. 6 is similar to FIG. 5 illustrating yet another yarn tensioning device.

FIG. 7 is a schematic diagram of an electrical circuit for a plurality of tension devices.

In FIG. 1 the invention is shown embodied in a unit comprising a power pack 10 and a yarn tensioning device 12. The power pack 10 can operate on a power source of 110 volt A.C. (not shown) or 220 vol-t A.C.

The power pack it) is shown as comprising a transformer 13 which has two primary coils 14 and \15 and a center tapped secondary coil 16. Referring to FIG. 2, the ends of primary coils -1.4 and 15 are brought out to terminals 17 by means of which the coils are connected to the A.C. power source and to each other in parallel to operate the unit 10' on 110 volt AC. and in series to operate on 220 volt A.C. Two diodes 18 respectively connected to the ends of the center tapped secondary coil 16 provide full wave rectification. The resulting pulsating DC. is supplied to an enregizing coil 20 of the yarn tensioning device 12 through a variable resistor 22 by means of which the DC. voltage is regulated. A control knob 24 is rotatable to increase or decrease the resistance of the resistor 22. A capacitor 26 is connected across the coil v2t) to smooth out the rectified current and reduce the pulsations to a selected level.

The electrical elements of the power pack 10 are en- 3,100,091 Patented Aug. 6, 1963 2 closed in a container 28. The control knob 24 of the variable resistor is mounted on the outside of the container which may be of any convenient material such as steel. The top 32 of the container 28 is comprised of steel or of nonmagnetic material such as a plastic, ceramic or brass.

The yarn tensioning device 12 is mounted on the top 32 of the container 28 of the power pack 10. The tensioning device 12 comprises an energizing coil 20' wound on a cylindrical coil form 34, composed of a nonmagnetic material such as nylon. The coil 20 is enclosed in a case 36 which is made of magnetic material such as steel, open at its upper end and with an aperture in the bottom coinciding with a similar aperture in the center of the top 32. A tubular center post 38 dimensioned to fit loosely in the center of coil form '34 is held in position by a bolt 40 that extends through the center post 38 and the apertures in the case 36 and the container top 3 2. A nut 41 engages the end of bolt 40 to firmly attach the center post 38 and the coil '20 in its case 36 to the top 32 of the power pack 10. Both the center post 38 and the bolt 40 are made of nonmagnetic materials. For example, the post may be of hard ceramic material and the bolt of brass. A lower friction disk 42 is annular in shape and has an outwardly flaring and downwardly extending flange forming its outer periphery. The diameter of the aperture of the disk 42 is not less than that of the nylon cylindrical form 34. The disk rests on top of the steel case 36 and surmounts the coil 20 and the nylon form 34 on which the coil 20 is wound. The disk is free to rotate about its axis and to move axially.

An upper friction disk 44 is also annular and similar in shape to the lower disk 42 but reversed and in addition has a downwardly extending concentric tubular stem 46 which loosely encircles the center post 38 and is itself loosely encircled by the coil form 34. The upper disk 44 is free to rest on the lower disk 42. Stem 46 extends almost to the bottom of the case 36 and acts both as a guiding sleeve for the disc 44 and as a solenoid plunger. The disk 44 is free to rotate about its axis and to move axially. The outer peripheral flange extends up-v wardly and outwardly and forms with the lower friction disk flange a V shaped entrance to guide the yarn between the friction disks. The plunger 46 and at least one of the disks 42, 44 are of magnetic material, e.g. steel.

A yarn to which tension is applied is guided between disks 42 and 44 and makes a partial turn around center post 38. When the ceil 30 is energized thorn the selfcontained DC. power pack 10 the resulting magnetic lines of force pass through the path comprising the lower disk 42 if it is made of magnetic material, the tubular plunger 46 and the side wall and bottom of the steel case 36 thereby exerting a solenoid diorce tending to draw the plunger 46 into the coil 20 and the upper disk 44 closer to the lower disk 42. In this case the force tending to draw the disks together is entirely solenoidal and is not substantially influenced by the air gap between the disks. In practice this means that variations in thickness of the yarn which necessarily increases the air gap between the disks will not substantially reduce the force drawing the disks together and thus af ect the tensioning of the yarn. If both disks are of magnetic material they provide lower reluctance of the magnetic circuit comprising the disks, plunger 46 and case 36.

If the lower disk 42 is made of nonmagnetic material and the upper disk 44 of magnetic material, the flux path is across the air gapto the upper disk 44 and then through the plunger 46 and the case 36 as before. The variation in air gap, caused by variations in the yarn thickness will vary the force tending to draw the disks together and thus vary the tensioning oi the yam. 'In either case, the

disks are urged into frictional engagement with the yarn running between them and thus apply a frictional drag to the yarn. The amount of drag depends on the force with which the upper disk 44- is drawn toward the lower disk '42 by the electromagnetic flux. The force can be readily adjusted by regulating the voltage of the current flowing through the coil 20 with the variable resistor 26 by rotating the knob 24, to increase or decrease the resistance in the circuit. The disks are light and are free to rotate, not being restricted by the friction of biasing springs of the inertia of weight means heretofore used to urge the disks toward each other. The frictional engagement of the disks with the yarn causes at least the upper disk to rotate and to carry the yarn between the disks in a bight 50 as illustrated in FIG. 3. The bight 50 insures that yarn enlargements that momentarily slow the yarn in passing through the yarn guiding means will not cause the yarn. to break but merely to momentarily reduce or eliminate the bight 50 thereby keeping tension on the yarn substantially uniform.

FIG. 4 illustrates an embodiment of the invention in which a solenoidal plunger 52 also acts as a center post and comprises a cylindrical element loosely fitting into the coil form 34. At the top, the cylindrical element has a radial flange 54 extending the periphery of the cylinder and having a diameter in excess of the diameter of the center apertures of the upper and lower disks. The underside of the flange 54 is provided with a suitable plastic bearing surface 55 composed of a material such as nylon or polytetrafluoroethylene commercially known as Teflonfi 'Ihe plunger 52 extends through the upper and lower disks to just clear of the bottom of the steel case 36 and is composed of a magnetic material. The upper and lower disks loosely fit around the cylindrical element of the plunger 52 and are free to rotate about it and to move axially. The radial flange 54 engages the upper disk by means of the plastic bearing 55. When the coil 20 is energized magnetic flux flows from the coil around the lower disk, the plunger member and the steel case and tends to draw the plunger into the coil as far as possible. This solenoidal action is transmitted through the flange 54 to the upper disk and tends to draw it closer to the lower disk thus increasing the frictional drag of the disks and tensioning the yarn, as explained heretofore. The plastic bearing 55 allows the upper disk to rotate about the plunger 52 as the yarn passes between the upper and lower disks. The plunger 52 is also free ly rotatable in the coil form 34 at least the inner surface of which is material having a low coefficient of friction, for example, nylon or Teflon.

FIG. 5 illustrates a modification of the plunger 56 and the steel case 58. The plunger 56 extends approximately halfway down into the center of the coil 20* and the bottom of the case 58 has a raised cylindrical center section 60 that extends up into the center of the coil 20 toward the plunger 56. A hearing pin 61 on the plunger 56 is rotatable in a hole in the cylindrical section to provide a low friction bearing for the plunger. The force tending to draw the upper and lower disks together is solenoidal and is not materially aflected by yarn size. It will be seen that the gap between the plunger 56 and the cylindrical section 60 is substantially at the center of the coil in an axial direction Referring to FIG. 6, still another modification of the steel case is illustrated. The central plunger 62 is similar to that shown in FIG. 5. The body of the coil case 64 is modified in that a raised center section 65 is conical in shape and the lower edge 66 of the plunger 62 is also conical so that any vertical movement of the plunger results in lesser variation of the gap between the plunger and the section 65. In other respects the structure and operation of the upper and lower disks and the flow of the magnetic flux are like FIGS. 4 and 5.

As described in FIG. 1, if the lower friction disk is made of magnetic material the solenoidal action of the parts extending into the center of the coil form is the only force tending to draw the disks together and the air gap between the two disks does not influence this force. If the lower friction disk is composed of nonmagnetic material and the upper disk is of magnetic material, then the forces tending to draw the disks together are a combination of the armature action of the top disk across the gap to the coil and the solenoidal action of the plunger. When thick yarns are used and the air gap is increased the electromagnetic force across the air gap is reduced and the tensioning is there-fore reduced. It is understood that both disks could be made of nonmagnetic material if a magnetic material annular cover for the open end of the coil enclosing case is provided to furnish a path 't'or the magnetic flux to the plunger.

While FIGS. 1 and 3 illustrate an embodiment in which each individual tension device is a self-contained unit with its own power pack that can be plugged into a conventional 60 cycle 110 volt or 220 volt A.C. outlet, the tension devices illustrated in FIGS. '1, 4, 5 and 6 can also be operated in groups or banks with a plurality of tension devices supplied with unidirectional current from a single power supply. It has been found advantageous to energize the tension devices with pulsating direct current rather than direct current of entirely uniform voltage. When non-pulsating current is used, it has been found that the twist in a yarn tends to accumulate ahead of the tensioning device and then passed through the device all at once so that the twist in the yarn after it has passed through the tensioning device is not uniform. When pulsating direct current is used, it has been found that the twist of the yarn passes through the tension device continuously and uniformly and does not accumulate ahead of the device.

In FIG. 7 there is shown an improved circuit which not only supplies pulsating direct current to a plurality of tension devices but further provides for varying both the frequency and the amplitude of the pulsations or ripple. The circuit is shown as comprising a variable voltage transformer comprising a variable auto transformer 70 and an output transformer 71 having a primary 71a and a secondary 71b. The transformer 70 is fed from a suitable power source for example mains 72. supplying 60 cycle alternating current. The output of the transformer 71 is connected through a full wave rectifier 73 to mains or buses 74 across which are connected the energizing coils 20 of a plurality of tension devices. A small potentiometer 76 is preferably connected in series with each of the tension devices to provide for individual adjustment of the devices as well as control of all of the tension devices simultaneously by varying the output voltage of the auto transformer 70. A condenser 77 connected across the output leads of the rectifier 73 tends to smooth out the ripple resulting from rectification of 60 cycle current.

Means is provided for superposing an alternating current of selected frequency and amplitude on the direct current output of the rectifier 73 so as to provide a pulsating current rather than direct current of entirely uniform voltage for energizing the coils 20 of the tension devices. Alternating current of selected frequency is provided by a variable frequency oscillator 80, the output of which is amplified by a power amplifier 81 connected to one of the mains 74. Power for operating the oscillator and ampliher is supplied from a suitable source for example by connection to the alternating current mains 72 that supply the transformer 70. The frequency of the oscillator 80 is variable through a selected range for example from 20 to 20,000 cycles a second. The amplification of the power amplifier 81 is also variable so as to vary the amount of ripple superposed on the direct current output of the rectifier 73. A choke coil 82 prevents the alternating current component introduced by the oscillator 80 and amplifier 81, being dissipated through the condenser 77.

It has been found desirable to use different frequencies and also diflerent amounts of pulsation depending on the particular installation of the tension devices and the character of the yarn being processed. It will be seen that the circuit illustrated in FIG. 7 provides great flexibility of operation to suit a wide variety of conditions.

While preferred embodiments of the invention have been shown by way of example in the drawings and particularly described, it will be understood that the features of the embodiments are mutually interchangeable and that the dimensions in configuration and the tensioning devices in. accordance with the invention may be varied to meet the circumstances and the requirements in each application. The scope of the invention is in no way limited to the preferred embodiments herein shown and described.

What We claim is:

1. A yarn tensioning device comprising a cup-shaped case comprising an outer peripheral wall and bottom wall of magnetic material, an annular electromagnet coil received in said case and having a central hole, a lower disk element overlying said coil and having a central hole, and an upper disk element overlying said lower disk element, said upper disk element having a central stem portion of magnetic material extending down through the central hole of said lower disk element and into said central hole of said coil whereby said upper disk element is drawn magnetically toward said lower disk element when said coil is energized to apply tension to a yarn running between said disk elements, said upper disk element and stem portion comprising a compo-site structure whereby said upper disk element by said stem portion is kept centered with said lower disk element and moves axially with said stem portion.

2. A yarn tensioning device comprising a cup-shaped case comprising an outer peripheral wall and bottom wall of magnetic material, an annular electromagnet coil received in said case and having a central hole, a circular sleeve portion of non-magnetic material in said hole, a lower disk element overlying said coil and having a central hole aligned with the hole of said coil, and an upper disk element overlying said lower disk element and having a stem portion which extends through the hole in said lower disk element and is rotatively received in said sleeve portion, said stem portion being drawn magnetically into said sleeve when said coil is energized, said upper disk element and stem portion comprising a composite structure whereby said upper disk element is kept centered with said lower disk element by said stem portion and moves axially with said stem portion so that said upper disk element is drawn toward said lower disk element to apply tension to a yarn running between said disk elements when said coil is energized.

3. A yarn tension device according to claim 2, in which said lower disk element is of magnetic material.

4. A yarn tension device according to claim 2, in which said sleeve portion is of plastic material aving a low coefficient of friction providing a low resistance bearing for said stem portion.

5. A yarn tension device comprising a cup-shaped case comprising an outer peripheral wall and bottom of magnetic material, said case being open at the top, an annular electromagnet coil received in said case and having a central hole, a circular sleeve portion of non-magnetic material in said hole, a lower disk element of magnetic material overlying said coil and contiguous with the peripheral wall of said case whereby said case and lower disk element together providing a continuous magnetic path extending around the bottomsides and top of said coil, said lower disk element having a central hole aligned with said central sleeve portion, and an upper disk element overlying said lower disk element and having a stem portion which extends through the hole in said lower disk element and is rotatively and axially movably received in said sleeve portion, said upper disk element and stem portion com prising a composite structure whereby said stem provides a bearing rotatively supporting said upper disk element and said upper disk element is movable axially with said stem, said stem being of magnetic material whereby said stem is drawn downwardly in said sleeve when said coil is energized and thereby draws said upper disk element toward the lower disk element to apply tension to a yarn running between said disk elements.

6. A yarn tension device according to claim 5, in which said upper disk element is also of magnetic material.

7. A yarn tension device according to claim 5, in which said stem portion is hollow.

8. A yarn tension device according to claim 5, in which upper disk element has a central hole aligned with the central hole of the lower disk element and in which said stem portion extends through the central hole in said upper disk element and has a flange at its upper end; whereby downwardly directed force on said stem portion is transmitted through said flange to said upper disk element.

9. A yarn tension device according to claim 8, in which a low friction thrust bearing is interposed between said flange and upper disk element.

10. A yarn tension device comprising a cup-shaped case comprising an outer peripheral wall and bottom of magnetic material, an annular electromagnet coil received in said case and having a central hole, a circular sleeve portion of non-magnetic material fitting closely in said hole, the bottom of said case having a central protuberance extending into said sleeve portion a distance less than the height of said coil, a lower disk element overlying said coil and having a central hole aligned with said sleeve portion and an upper disk element overlying said lower disk element and having a central stem portion of magnetic material extending through said hole in said lower disk element and freely received in said sleeve, the lower end of said stem portion being slightly spaced from the upper end of said protuberance when said device is in operative condition with a yarn between said disk elements, whereby said stem portion and upper disk element are magnetically drawn downwardly to grip said yarn when said coil is energized.

11. A yarn tension device according to claim 10 in which said protuberance is cone-shaped and the lower end of said stem portion is hollow and formed with a conical surface substantially complementary to said protuberance.

12. A self-contained individual yarn tension device comprising a container having a top, an upwardly opening cup-shaped case mounted on said container top, said case comprising an outer peripheral wall and bottom of magnetic material, an annular electnomagnet coil received in said case and having a central hole, a lower disk element overlying said coil and having a central hole aligned with the hole of said coil, an upper disk element overlying said lower disk element and having a stem portion of magnetic material extending down through the central hole in said lower disk element and into the central hole of said coil so that said stern portion and upper disk element are drawn downwardly when said coil is energized to apply tension to a yarn running between said disk elements, a power pack contained in said container and having an AC. input and DC. output, said power pack comprising means fior converting alternating current to direct current and control means for varying the direct current output of said power pack, said control means having a control element accessible on the outside of said container for varying said direct current output, means for connecting the input of said power pack to an AC. power supply and means connecting the output of said power pack to said coil, whereby said device is operable directly from an AC. power line.

13. A yarn tensioning device comprising opposed friction disks mounted for rotation and relative axial movement and receiving yarn running between their opposing surfaces, electromagnetic means for drawing said disks toward one another to apply tension to said yarn, said yarn and disks having natural frequencies of oscillation, and means fior energizing said electromagnetic means, said energizing means comprising a transformer having a primary winding and a secondary winding, means for connecting said primary winding to an alternating current power supply, a full wave rectifier having an input connected to said secondary winding and an output, means connecting the output of said rectifier to said electromagnetic means to supply direct current to said electromagnetic means, a variable frequency oscillator having an input and an output, means connecting the input of said oscillator with a power supply, an amplifier having an input connected to the output of said oscillator and an output, means connecting the output of said amplifier to said electromagnetic means to superpose an alternating current onthe direct current supplied by said rectifier, and means for variably regulating the frequency of said oscillator.

14. A yarn .tensioning device according to claim 13, in which said means connecting said rectifier with said elem tromagnetic means comprises a capacitance connected across the output of said rectifier and an inductance connected 'between said capacitance and said oscillator to inhibit dissipation of the alternating current output of said oscillator by said capacitance.

References Cited in the file of this patent UNITED STATES PATENTS 1,301,412 'Elmen Apr. 22, 1919 1,943,524 Godsey Jan. 16, 1934 2,532,723 Knoop Dec. 5, 1950 2,698,590 Garbo Ian. 4, 1955 2,907,535 Mindheim ct a1. Oct. 6, 1959 

1. A YARN TENSIONING DEVICE COMPRISING A CUP-SHAPED CASE COMPRISING AN OUTER PERIPHERAL WALL AND BOTTOM WALL OF MAGNETIC MATERIAL, AN ANNULAR ELECTROMAGNET COIL RECEIVED IN SAID CASE AND HAVING A CENTRAL HOLE, A LOWER DISK ELEMENT OVERLYING SAID COIL AND HAVING A CENTRAL HOLE, AND AN UPPER DISK ELEMENT OVERLYING SAID LOWER DISK ELEMENT, SAID UPPER DISK ELEMENT HAVING A CENTRAL STEM PORTION OF MAGNETIC MATERIAL EXTENDING DOWN THROUGH THE CENTRAL HOLE OF SAID LOWER DISK ELEMENT AND INTO SAID 